The goal of this project is to evaluate the feasibility (Phase I) and demonstrate the safety and effectiveness (Phase II) of a novel peripheral nerve stimulation therapy to treat pain and enable early rehabilitation after total knee arthroplasty (i.., replacement), resulting in improved function, independence, and quality of life. Total knee arthroplasty is a surgical procedure to treat disabling knee conditions, and approximately half of all patients experience moderate to severe pain during the first four weeks after surgery that can interfere with rehabilitation. Opioids carry risks of debilitating side effects that interfere with rehabilitation. Nerve blocks are not suited for extended use at home due to risks of infection, local anesthetic toxicity, and falls from motor block. A non-opioid therapy that enables patients to engage fully in physical rehabilitation during the first 4 weeks after surgery is needed for pai after total knee arthroplasty. Patients who are unable to engage fully in rehabilitation during thi period risk substantial delays in returning to normal function. In Phase I, the feasibility of providing immediate pain relief and improvements in function will be evaluated during in a case series study of 16 individuals suffering from postoperative pain and reduced knee range of motion following total knee arthroplasty. Electrical stimulation will be delivered to the nerve innervating the region of pain with the goal of evoking comfortable sensations without unwanted motor activation. The aims are to determine if stimulation generates immediate reductions in pain, increases knee range of motion, and improves mobility. If all aims are successful, Phase II of the research will be conducted. In Phase II, our approach to relieve pain and improve function during the critical four weeks following total knee arthroplasty will be evaluated in a randomized placebo-controlled trial enrolling 40 individuals scheduled to undergo surgery. A percutaneous lead will be placed preoperatively in each subject, and active stimulation (Treatment Group) or sham (placebo) stimulation (Control Group) will be delivered for four weeks after surgery. The Phase II aims are to determine if the Treatment Group (compared to the Control Group) has 1) significantly greater reductions in pain while walking, 2) significantly improved knee function, independence, and quality of life, and 3) significantly improved endurance and mobility. If Phase II is successful, then these data will support FDA 510k clearance for this assistive technology to improve function, independence, and quality of life of patients following total knee arthroplasty. The commercialization of our novel peripheral nerve stimulation therapy will substantially impact clinical practice by providing surgeons and their patients with a non-opioid, minimally-invasive, simple, safe, and effective treatment option, resulting in pain relief and improved physical function that extends into the post- discharge home rehabilitation period, enabling full participation in rehabilitation and achievement of greater mobility and independence.